scholarly journals The study of convex-dual-layer remote phosphor geometry in upgrading WLEDs color rendering index

2021 ◽  
Vol 11 (5) ◽  
pp. 3890
Author(s):  
Huu Phuc Dang ◽  
Nguyen Thi Phuong Loan ◽  
Nguyen Thi Kim Chung ◽  
Nguyen Doan Quoc Anh
Keyword(s):  
Double Layer ◽  
Layer Structure ◽  
Light Emitting Diode ◽  
Light Output ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Red Phosphor ◽  
Remote Phosphor ◽  
Color Rendering Index ◽  
Color Rendering

<span>The white-light light-emitting diode (LED) is a semiconductor light source that usually has one chip and one phosphor layer. Because of that simple structure, the color rendering index (CRI) is really poor. Therefore, structure with double layer of phosphor and multiple chips has been studied with the phosphorus proportions and densities in the silicone are constantly changed to find the best option to improve optical properties. In research, we use red phosphor Ca5B2SiO10:Eu3+ layer to place above the yellow phosphor one, and both of them have a convex design. Then, the experiments and measurements are carried out to figure out the effects of this red phosphor as well as the convex-double-layer remote phosphor design on the LED’s performances. The measured results reveal that the light output is enhanced significantly when using convex-dual-layer structure instead of the single-layer design. Additionally, the Ca5B2SiO10:Eu3+ concentration benefits CRI and CQS at around 6600 K and 7700 K correlated color temperature (CCT). Yet, the lumen output shows a slight decline as this red phosphor concentration surpass 26% wt. Through the experiments, it is found that a double layer of chip and double phosphorus is the best structure which could support the quality of CRI and luminous flux.</span>

scholarly journals Warm-white light-emitting diode with high color rendering index fabricated by combining trichromatic InGaN emitter with single red phosphor

2015 ◽  
Vol 23 (7) ◽  
pp. A232 ◽  
Author(s):  
Jinn-Kong Sheu ◽  
Fu-Bang Chen ◽  
Yen-Chin Wang ◽  
Chih-Chiang Chang ◽  
Shih-Hsien Huang ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Red Phosphor ◽  
Light Emitting ◽  
Warm White Light ◽  
Color Rendering Index ◽  
Color Rendering

scholarly journals Enhance the chromatic uniformity and luminous efficiency of WLEDs with triple-layer remote phosphor structures

2020 ◽  
Vol 10 (6) ◽  
pp. 6244
Author(s):  
Nguyen Thi Phuong Loan ◽  
Anh Tuan Le
Keyword(s):  
Layer Structure ◽  
Luminous Flux ◽  
Color Temperature ◽  
Color Quality ◽  
Important Target ◽  
Triple Layer ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
Color Rendering ◽  
Better Than

The angular color uniformity (ACU) with the ability to evaluate chromatic performance of WLED has become an important target to achieve in producing higher-quality WLEDs. This paper studies the ACU enhancing effects of novel triple-phosphor configuration in lighting devices with remote phosphor structure. Moreover, the optical influences of remote phosphor structure with three phosphor layers (TL) on WLEDs properties are calculated and compared to the dual-layer (DL) one for reference. The experiments are applied to devices at 5 distinct correlated color temperature ranging from 5600-8500 K. The results presented that DL structure attains better color rendering index (CRI) than the TL one. Meanwhile, in terms of color quality scales (CQS), TL model shows higher values at all ACCTs, compared to the DL. Moreover, the luminous flux of DL configuration is lower than that of TL structure. In addition, the diversion of color temperature depicts as D-CCT in TL structure is much better than the value in DL structure, especially at high ACCT as 8500 K, which means TL is good for chromatic uniformity of high ACCTs WLEDs. These results proved that the triple-layer structure is superior and more effective to apply for acquiring the enhancement of WLEDs package.

scholarly journals The Impacts of Red-emitting Mg2TiO4:Mn4+ Phosphor on Color Quality of Dual-layer Remote Phosphor Configuration

2019 ◽  
Vol 3 (3) ◽  
pp. 464
Author(s):  
Hsiao-Yi Lee ◽  
Phan Xuan Le ◽  
Doan Quoc Anh Nguyen
Keyword(s):  
Red Light ◽  
Mie Scattering ◽  
Conformal Structure ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Creative Commons ◽  
Color Quality ◽  
Remote Phosphor ◽  
Color Rendering

In terms of luminous flux, the remote phosphor structure is better than conformal structure or in-cup phosphor structure, however, this structure often has inferior color quality compared to the others. As a result, many studies have been conducted to nd a solution to the drawback mentioned above. In this research, we are after the same goal using WLEDs structure with color temperature of 5600 K and come to the conclusion that dual-layer phosphor structure can improve the color rendering index (CRI) and the color quality scale (CQS). The concept of the research is to place red phosphor layer Mg2TiO4:Mn4+ on a yellow phosphor layer YAG:Ce3+ and locate the concentration of Mg2TiO4:Mn4+ that allows the color quality to reach the highest value. The result shows that Mg2TiO4:Mn4+ benets CRI and CQS, more specifically, the addition of Mg2TiO4:Mn4+ in WLEDs boosts the red light component, thus, enhancing CRI and CQS. However, it is demonstrated through the application of Mie-scattering theory and Lambert-Beer law that when the concentration of Mg2TiO4:Mn4+ exceed the limit, it can harm the luminous flux of WLEDs. The result of this research is a valuable contribution to improving the techniques of manufacturing better WLEDs with higher white light quality.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

scholarly journals Novel lighting properties of white LEDs with two-layered remote phosphor package using red-emitting α-SrO·3B2O3:Sm2+ phosphor

2017 ◽  
Vol 35 (3) ◽  
pp. 618-625
Author(s):  
Tran Hoang Quang Minh ◽  
Nguyen Huu Khanh Nhan ◽  
Nguyen Doan Quoc Anh ◽  
Hsiao-Yi Lee
Keyword(s):  
Lower Layer ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Light Emitting ◽  
White Leds ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
White Light Emitting Diodes ◽  
Color Rendering

AbstractThis paper investigates a method for improving the lighting performance of white light-emitting diodes (WLEDs), packaged using two separating remote phosphor layers, yellow-emitting YAG:Ce phosphor layer and red-emitting α-SrO·3B2O3:Sm2+ phosphor layer. The thicknesses of these two layers are 800 μm and 200 μm, respectively. Both of them have been examined at average correlated color temperatures (CCT) of 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor has been varied from 2 % to 30 % in the upper layer, while in the lower layer the yellow phosphor concentration was kept at 15 %. It was found interesting that the lighting properties, such as color rendering index (CRI) and luminous flux, are enhanced significantly, while the color uniformity is maintained at a level relatively close to the level in one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer have been revised by combining Kubelka-Munk and Mie-Lorenz theories. Through the analysis, it is demonstrated that the packaging configuration of two-layered remote phosphor that contains red-emitting α-SrO·3B2O3:Sm2+ phosphor particles provides a practical solution to general WLEDs lighting.

scholarly journals Triple-layer remote phosphor structure: a selection of the higher color quality and lumen efficiency for WLEDs

2021 ◽  
Vol 10 (4) ◽  
pp. 1960-1967
Author(s):  
Phan Xuan Le ◽  
Le Hung Tien
Keyword(s):  
Glass Matrix ◽  
Layer Structure ◽  
Mie Scattering ◽  
Phosphor Layer ◽  
Light Emitting ◽  
Color Quality ◽  
Triple Layer ◽  
Remote Phosphor ◽  
White Light Emitting Diodes ◽  
Color Rendering

To enhance color quality of glass-based phosphor-converted white light-emitting diodes (pc-WLEDs) with multi-layer remote phosphor layer structures, two phosphors, green CdS:In and red ZnS:Te,Mn, are integrated into the glass matrix and applied to the dual-layer and triple-layer WLED packages. The attained results were examined with Mie-scattering theory and Lambert-Beer law. The dual-layer showed significant enhancement in color rendering index (CRI), in the range of approximate 80-90. Meanwhile, CRI in the triple-layer was lower and stayed around 66. In terms of color quality scale (CQS), a more overall color evaluating index, triple-layer structure helps the glass-based WLED achieve higher value than the dual-layer. The triple-layer is also beneficial to the luminous efficacy, according to the experimented results. Thus, the triple-layer structure can be used to strengthen the benefit of the glass matrix used in WLED products.

scholarly journals Building superior lighting properties for WLEDs utilizing two-layered remote phosphor configurations

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Guo-Feng Luo ◽  
Nguyen Thi Phuong Loan ◽  
Le Van Tho ◽  
Phung Ton That ◽  
Nguyen Doan Quoc Anh ◽  
...  
Keyword(s):  
Red Light ◽  
Mie Scattering ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Green Phosphor ◽  
Red Phosphor ◽  
Color Quality ◽  
Remote Phosphor ◽  
Chromatic Properties

AbstractThe remote phosphor structure produces higher luminous flux but delivers poorer color quality than the conformal or in-cup phosphor structure. To eliminate this weakness, researchers have attempted to improve the chromatic properties of remote phosphor package. This study tends to enhance lighting features for WLEDs including color quality and luminous flux in general or color rendering index (CRI) and color quality scale (CQS) in particular by applying dual-layer remote phosphor structure. In the simulation section, we utilize two identical LEDs that only differ in correlated color temperature values which are 6600 K and 7700 K. The study offers an idea of placing a yellow-green phosphor layer SrBaSiO4:Eu2+ or a red phosphor layer SrwFxByOz:Eu2+,Sm2+ on the yellow phosphor layer YAG:Ce3+ and then modifying the concentrations of SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ to the suitable values to improve the color quality and lumen output of WLEDs. The results show that red phosphor layer SrwFxByOz:Eu2+,Sm2+ has a significant influence on CRI and CQS improvement. Particularly, the increase of SrwFxByOz:Eu2+,Sm2+ concentration leads to increased CRI and CQS because the red light component increases in WLEDs. On the other hand, the green phosphor layer SrBaSiO4:Eu2+ only brings benefit to the luminous flux. However, the WLEDs’ luminous flux and color quality drop sharply, when SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ concentrations rise extremely, which is verified based on the Mie-scattering theory and the Lambert-Beer law. In short, the article provides general knowledge and primary information for the production of higher-quality WLEDs.

scholarly journals Hydrothermal synthesis of narrow-band red emitting K2NaAlF6:Mn4+phosphor for warm-white LED applications

RSC Advances ◽  
2017 ◽  
Vol 7 (72) ◽  
pp. 45834-45842 ◽  
Author(s):  
Haiming Cheng ◽  
Yan Song ◽  
Guixia Liu ◽  
Dan Li ◽  
Xiangting Dong ◽  
...  
Keyword(s):  
Narrow Band ◽  
Red Light ◽  
Color Temperature ◽  
Light Radiation ◽  
White Led ◽  
Hydrothermal Route ◽  
Red Phosphor ◽  
Truncated Octahedron ◽  
Color Rendering Index ◽  
Color Rendering

The truncated octahedron shaped K2NaAlF6:Mn4+was preparedviahydrothermal route, which emits red light under blue light radiation. Warm WLEDs fabricated by the obtained red phosphor show lower color temperature and higher color rendering index.

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